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United States Patent |
5,146,067
|
Sloan
,   et al.
|
September 8, 1992
|
Prepayment metering system using encoded purchase cards from multiple
locations
Abstract
A prepayment system for dispensing utilities using mag-stripe cards is
disclosed wherein an accounting computer in a central office is used in
conjunction with point-of-sale machines for encrypting a value message
which is written onto the mag-stripe of a mag-stripe card. The value
message contains information relating to the amount of utilities purchased
by the customer, the utility rates, the site identification number, and a
unique password formed by the site number, a hidden number, and the
transaction number. The mag-stripe card is carried by mail or in person to
the consumer's home or office and inserted into a mag-stripe card reader
attached to microprocessor-based utility control device. This utility
control device is capable of reading and decoding the mag-stripe card and
storing the value information into memory for use in monitoring the
utility usage of the customer and disconnecting or connecting the utility
based on the amount of utilities purchased.
Inventors:
|
Sloan; Joseph W. (Nashville, TN);
Snyder; Harry P. (Brentwood, TN);
Foster; Joseph W. (Nashville, TN);
Day; Mark C. (Nashville, TN);
Berg; Timothy G. (Brentwood, TN);
Jarreau; Michael (Brentwood, TN);
Miller; Mark P. (Nashville, TN);
Bush; A. Michael (Nashville, TN)
|
Assignee:
|
CIC Systems, Inc. (Brentwood, TN)
|
Appl. No.:
|
464328 |
Filed:
|
January 12, 1990 |
Current U.S. Class: |
235/381; 235/449; 340/5.9; 705/412 |
Intern'l Class: |
G06F 007/08 |
Field of Search: |
235/381,380,449
364/464.04
340/825.35,825.33
|
References Cited
U.S. Patent Documents
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| |
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| |
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3676875 | Jul., 1972 | Adams et al.
| |
3778637 | Dec., 1973 | Arita.
| |
3835301 | Sep., 1974 | Barney.
| |
3885130 | May., 1975 | Moulton et al.
| |
3935933 | Feb., 1976 | Tanaka et al.
| |
4019135 | Apr., 1977 | Lofdahl.
| |
4020325 | Apr., 1977 | Pfost et al.
| |
4024379 | May., 1977 | Pfost et al.
| |
4077061 | Feb., 1978 | Johnston et al.
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4162530 | Jul., 1979 | Kusui et al.
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4240030 | Dec., 1980 | Bateman et al.
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4291375 | Sep., 1981 | Wolf.
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4345311 | Aug., 1982 | Fielden.
| |
4351028 | Sep., 1982 | Peddie et al.
| |
4399510 | Aug., 1983 | Hicks.
| |
4442492 | Apr., 1984 | Karlsson et al.
| |
4542469 | Sep., 1985 | Brandyberry et al.
| |
4568934 | Feb., 1986 | Allgood.
| |
4575622 | Mar., 1986 | Pellegrini.
| |
4629874 | Dec., 1986 | Pugsley et al.
| |
4731575 | Mar., 1988 | Sloan.
| |
4777354 | Oct., 1988 | Thomas | 235/380.
|
4795892 | Jan., 1989 | Gilmore et al. | 235/381.
|
4803632 | Feb., 1989 | Frew et al.
| |
4906828 | Mar., 1990 | Halpern | 235/380.
|
Foreign Patent Documents |
2188467 | Sep., 1987 | GB.
| |
2208955 | Apr., 1989 | GB.
| |
Primary Examiner: Trafton; David
Attorney, Agent or Firm: Merchant, Gould, Smith, Edell, Welter & Schmidt
Claims
What is claimed is:
1. A prepaid utility dispensing system, comprising:
(a) at least one card dispensing station comprising means for encoding a
mag-stripe card with value and account information arising from a purchase
of prepaid utility services, the value and account information comprising
a present rate, at least one future rate and a date when the conversion to
the future rates are to occur; and
(b) a utility dispensing device resident at a customer site for dispensing
utility services in accordance with the value and account information
encoded on the mag-stripe card, wherein the present rate and the future
rates determine how the utility dispensing device is to value the utility
service dispensed, and the date determines when the future rates are to be
placed into effect by the utility dispensing device, regardless of when
the customer buys the mag-stripe cards.
2. The system as set forth in claim 1 above, wherein the utility dispensing
device comprises means for comparing a date encoded on the mag-stripe card
and a date stored by the utility dispensing device, and means for
re-setting the date stored by the utility dispensing device when the date
encoded on the mag-stripe card is a later date, so that a correct date may
be maintained by the utility dispensing device following an extended power
outage.
3. A prepaid utility dispensing system, comprising:
(a) a utility dispensing device resident at a customer site for dispensing
utility services in accordance with a value thereof as encoded on a
mag-stripe card;
(b) status window means, connected to the utility dispensing device, for
displaying status and system control indications for the utility
dispensing device; and
(c) means for selecting among a plurality of languages to use for
displaying the status and system control indications, the means for
selecting comprising means for reading a mag-stripe card, for examining a
parameter supplied by the mag-stripe card, and for choosing the language
for the status window means in accordance with the parameter.
4. A prepaid utility dispensing system, comprising:
(a) at least one card dispensing station comprising means for encoding a
mag-stripe card with value and account information arising from a purchase
of prepaid utility services, the value and account information comprising
lifeline protection information indicating a maximum load level and a
termination date; and
(b) a utility dispensing device resident at a customer site for dispensing
utility services in accordance with the value and account information
encoded on the mag-stripe card, wherein the maximum load level determines
the rate of utility consumption the utility dispensing device is to allow
when the prepaid utility services are depleted, and wherein the
termination date determines when the lifeline protection is to be
terminated unless the customer has made additional purchases of prepaid
utility services.
5. The system as set forth in claim 4 above, wherein the minimal supply
level comprises a minimum number of seconds allowed per disk revolution of
the utility dispensing device, so that a power switch in the utility
dispensing device is instructed to open when a time period for the disk
revolution is less than the minimum number of seconds, thereby indicating
that an allowable load is being exceeded.
6. The system as set forth in claim 5 above, wherein the utility dispensing
device further comprises:
means for keeping the power switch open for a predetermined period of time
to allow the customer time to uncouple offending appliances from the
utility service; and
means for re-closing the power switch at the end of the predetermined
period to thereby restore utility services.
7. The system as set forth in claim 4 above, wherein the card dispensing
station further comprises means for specifying a maximum load level and a
termination date for each customer, thereby allowing for maximum
flexibility in setting different standards for different customers, based
upon the customers' unique requirements and their ability to pay.
8. The system as set forth in claim 4 above, wherein the utility dispensing
device further comprises means for accumulating negative values for
utility services dispensed under the lifeline information, so that the
negative values are subtracted from the value of a next purchase of
prepaid utility services.
Description
FIELD OF THE INVENTION
This invention relates to prepayment utility meter units, and more
particularly to a more secure method and apparatus for providing
prepayment information from more than one utility sales location to the
customer site such that the messages are not subject to alternation,
counterfeiting or fraud.
BACKGROUND OF THE INVENTION
Utility companies have historically used the method of reading meters and
rendering bills as a means for collecting for electric, gas, and water
service after it has been used by the customer. More recently, prepayment
metering systems have been proposed in the prior art as a technology for
overcoming some of the shortcomings of the traditional billing system.
These prepayment systems were designed so that the purchase of a supply of
electricity, gas, or water is made at a central station such as the gas or
electric utility office, and the information regarding the amount of the
purchase is then communicated to the customer site where the utilities are
consumed. At the customer site a metering device is installed which is
designed to receive the prepayment communication information and credit
the user with the amount purchased at the central site. These types of
proposed prepayment metering systems will reduce the overall cost of
utility distribution by reducing or eliminating meter reading expenses,
bad debt collection, account transfer expenses and credit department
expenses, while at the same time providing a greater awareness on the
consumer's part as to his or her consumption habits.
An example of a prior art utility company device of the aforementioned type
is described in U.S. Pat. No. 4,731,575 to Joseph W. Sloan, which
describes a microprocessor-controlled utility device which receives
payment information on a mag-stripe card and allows the utility service to
continue so long as the pre-purchased amount has not been exhausted. This
device includes a display that the customer can use to monitor the utility
usage at the customer site, including present rate of use, amount used the
previous day, and the amount remaining.
One characteristic inherent in the prepayment for utility service is the
possibility of service being interrupted because of a failure of the
customer to make a timely purchase before the supply is exhausted.
Therefore, in order for a prepayment system to be generally acceptable to
the majority of customers, it is necessary that the customer be able to
make additional purchases at any time of the day or night from one or more
convenient stations located nearby. These remote purchase stations may be
attended or unattended, but are most cost-effective if unattended.
A primary concern of prepayment metering systems is a communications method
which cannot be breached by unauthorized personnel for the purpose of
obtaining or continuing the utility service without proper payment. An
example of an effective prior art communications security method is the
sequential password described in the aforementioned U.S. Pat. No.
4,731,575. However, that system does not provide the flexibility and
customer convenience required for operating large numbers of card purchase
stations serving very large numbers of utility customers over a wide
geographic area.
Another concern of prepayment is the opportunity for the customer to
pre-purchase a very large quantity of utility service at the present lower
rate prior to an announced increase in rates in order to continue to use
service for an extended period of time at the lower rate. Furthermore,
with the elimination of monthly meter reading, the opportunity for utility
personnel to observe possible tampering or meter failure is greatly
reduced.
The present invention overcomes these and other shortcomings of the prior
art utility prepayment systems by providing a simple, low-cost
communications and control system based primarily on existing and
off-the-shelf components and by expanding the sequential password scheme
such that the customer premise equipment will recognize and accept value
and other information encoded on cards issued from several different
purchase locations. The present invention uses an encoding scheme and
relies on other mechanical and monitoring devices to bolster the overall
security and reliability of the system.
SUMMARY OF THE INVENTION
According to the present invention there is provided a prepayment system
for dispensing utilities using mag-stripe cards. A sales and accounting
computer in the office is used in conjunction with point-of-sale machines
for encrypting a value message which is written onto the mag-stripe of a
mag-stripe card. The value message contains information relating to the
amount of utilities purchased by the customer, the utility rates, the site
identification number, and a unique password formed by the site number, a
hidden number, and the transaction number. The mag-stripe card is carried
by mail or in person to the consumer's home or office and inserted into a
mag-stripe card reader attached to microprocessor-based utility control
device. This utility control device is capable of reading and decoding the
mag-stripe card and storing the value information into memory for use in
monitoring the utility usage of the customer and disconnecting or
connecting the utility based on the amount of utilities purchased.
The present invention provides a method and apparatus for the customer to
purchase the mag-stripe value cards directly from the utility office by
either mail order, in person or pre-arranged periodic bank drafts, or from
unattended machines in convenient neighborhood locations which are
accessible to the customer 24 hours per day. These unattended machines
will recognize and accept local paper currency in common denominations,
and provide a properly encoded card to the customer. The customer may use
a previously used mag-stripe card to identify the location for which the
utility is being purchased, or the location number may be entered by the
customer by pressing numbered keys provided on the machine. It is not
necessary to have a previously purchased card in order to make a purchase,
since a supply of blank cards is available at the unattended machine. Two
cards may be purchased at one time so that one may be kept in reserve for
use in an emergency. The sequential password scheme provided by this
invention allows any such reserve card to be used at any time, without
regard to the sequence, and without any compromise of communications
security.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in more detail by way of example with
reference to the accompanying drawings in which like numerals refer to
like components throughout the several views:
FIG. 1 is a pictorial diagram showing the main components in the prepayment
system;
FIG. 2 is a block diagram of the un-attended mag-stripe card dispensing
machine, which may be located on a counter of a business establishment or
mounted in a wall;
FIG. 3 is a block diagram of the control electronics located at the
customer premises for accepting the prepayment mag-stripe cards and
controlling the utility supply to the customer equipment;
FIG. 4 describes its structure of the New Account Records transmitted to
the encoding machines;
FIG. 5 describes the structure of the message encoded on a mag-stripe card;
FIG. 6 describes the structure of the Transaction Records communicated to
the central Accounting Computer;
FIG. 7 describes the structure of the Location Records maintained by the
encoding machines; and
FIG. 8 describes the structure of the Transaction Records maintained in the
encoding machine;
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In the preferred embodiment of the present invention, a conventional
off-the-shelf induction disc electric utility meter 600 is attached to a
utility meter extension sleeve 500 or other housing, also commonly
available as an off-the-shelf device, which incorporates an integral power
disconnect switch 503. The utility meter 500 is designed with integral
photoelectric cells 601 to measure shaft revolutions of the meter disk
602. The disconnect switch 503 is mechanically latching and of a capacity
to match the service entrance size (typically 200 amps), which can be
remotely controlled by the indoor display 400 and control sleeve 500. This
indoor display box 400 is attached inside the customer premises and
connects to the control sleeve 500 at the meter socket extension sleeve
and the kWh utility meter 600 by means of a small 4-conductor cable 451,
or alternatively by using the house wiring 453 as a powerline carrier. The
indoor display box 400 includes a mag-stripe card reader 405 and a
microprocessor-controlled system to provide for status display 403 and
system control.
The mag-stripe cards 300 are used to convey encoded and encrypted value and
account information to the customer's premises using ANSI standard
mag-stripe type credit cards. These cards are encoded at the utility site
or at any one of any attended or un-attended card dispensing stations 200
with a commonly available mag-stripe card writer which communicates as
necessary with an Accounting Computer 100 which records the customer
purchases and encrypts the next card image to be used. The Accounting
Computer 100 and the indoor display 400 and control sleeve 500 at the
customer site are both programmed with identical encryption and decryption
algorithms to provide for a secure method of transferring information. The
mag-stripe card 300 is encoded with a minimum amount of necessary
information for conveying said value information, which includes a
sequential password system known only to the transmitting and receiving
stations so that value mag-stripe cards cannot be reused, and lost or
stolen mag-stripe cards may be replaced with duplicate cards without fear
of fraud. The sequential passwords are derived as a combination of the
user account number, customer site ID, sequence number of the transaction,
and the number of the encoding station 200. This information can be
encoded into a password using a variety of mathematical algorithms and
truncated into a unique non-repeating password. The password root for each
account is provided by the Accounting Computer 100 as a part of a card
image provided to each encoding dispensing machine 200 in the designated
geographic area. At the time a card purchase is made, a unique password
suffix and the value of the purchase are added by the computer at the card
encoding station 200. The Accounting Computer 100 communicates at least
once each day with all card encoding machines 200 to collect information
regarding purchases, update the utility company's files, and provide new
card images to the encoding machines 200 for those accounts where card
purchases were made that day. In the preferred embodiment, each encoding
machine 200 will carry card images for the next two transactions for each
customer account, so that a customer may make two purchases the same day
from the same encoding machine 200.
The customer indoor display 400 is programmed such that it will accept
cards from any of several card encoding machines 200 (typically up to 7).
The encoding machines to be used by a specific customer display 400 are
not preprogrammed when the display 400 is installed, but are established
by the customer's buying patterns. Each time the display 400 recognizes
the customer has bought a mag-stripe card from a new and previously unused
encoding machine 200, the display 400 will open a new series of passwords
for future interaction with that encoding machine. The display 400 will
generate the next three sequential passwords it should look for from that
encoding machine 200. Then, each time one of those passwords is used, it
will generate and store the next password which should appear in that
sequence. Thus it is possible, in the preferred embodiment, for the
display 400 to have up to 21 active passwords which it will accept (three
from each of 7 dispensing machines 200). This scheme allows any regular
value card 300 to be kept indefinitely for use as a reserve card for
emergencies, regardless of when or where it was purchased, and when it is
used.
This technique for the encoding and encrypting of value password
information is simple and economical to implement, but highly effective in
its security since the environment in which this system is to be used is
already secured with tamper indicating tabs which are periodically checked
for tampering. In addition, since conventionally available utility meters
600 are used in this application, the mechanical dials indicating utility
usage are still in place, and can be periodically read by a service person
from the utility company to verify the account information on record at
the utility site.
Nevertheless, it is desirable for the utility company to become aware of
any meter tampering event as quickly as possible so that corrective action
can be taken. To this end, the control sleeve 500 contains means of
detecting removal of the meter, the presence of a magnetic field, and disk
rotation time intervals not proportional to the current being used. When
any of these tampering events are detected, the indoor display 400 will
cease to function in its normal manner, and the status display window 403
will show only a numbered error code which will identify the type of
tamper event which occurred. This change of operating mode will not occur
immediately, but at some number of hours following the event so that the
customer will not necessarily attribute the error code to this tampering
activity. It is expected that in most case, this apparent malfunction will
be reported to the utility so that proper functionality will be restored.
It is also desirable that any malfunction of the display 400 or sleeve 500
be reported to the utility company as quickly as possible. Therefore,
internal diagnostics programs will identify various component failures,
such as the failure of a photo cell 601 that senses rotation of the meter
disk 602, and the appropriate error code will be shown in the display
window 403, to the exclusion of all other information. Again, it is
assumed that if the customer can no longer read the amount remaining or
other normal displays, he will report the malfunction to the utility
company.
The prepayment metering system is shown in a pictorial block diagram in
FIG. 1. Accounting Computer 100 is the "host controller" at the utility
company office. If the system contains only one card encoding station 101,
the Accounting Computer 100 may be a Personal Computer with the mag-stripe
card encoder 105 attached directly to a serial port and operate
substantially in the manner as described in the aforementioned prior art.
If more than one card encoding stations 101 and/or 200 are used,
Accounting Computer 100 will be a network file server, in which case it
has the capability of serving a large number of on-line manned
card-encoding stations consisting of a card encoder 105, CRT 102, keyboard
103, and dot matrix printer 104, and a large number of unmanned card
dispensing machines 200 which may be located off the utility company
premises. These remote, unmanned machines 200 are shown in the diagram as
being interrogated periodically by dial-up telephone modems 108 on a
periodic basis, but this communication may also be accomplished by a
physical exchange of data diskettes.
The Accounting Computer 101 includes a library of all the screen images and
instructions in such form and design that it is replicated in different
languages. In a bilingual community such as Miami or Quebec, instructions
on the CRT screen 102 may be presented in Spanish or French or English at
the option of the operator, and may be keyed to each operator's access
password such that the preferred language appears automatically for each
operator. Other languages, such as Japanese and Korean, may be included in
the library to the extent that they are already available in the PC
environment. The number of languages which can be accommodated in the
preferred embodiment is 16, but this can be expanded with additional
memory if desired.
FIG. 2 shows a block diagram of the unattended encoding machine 200. Except
for the housing, it is assembled from commercially available components to
perform remote, unattended point-of-sale card encoding functions and other
procedures in accordance with a unique program encoded into its central
processing unit 201; a CRT or LCD type message screen 202 to provide
interactive instructions to the customer; a key pad 203 with numbers 0
through 9 and additional dedicated keys, all such keys being presented as
physical buttons or as images on a touch-screen CRT; a
currency-recognizing device 204 which will capture and read the value of
inserted currency of commonly-used denomination; a mag-stripe card reader
and encoder 205, either motor driven or a swipe type, which may or may not
have the capability to print the date, amount of purchase, and other
identifying information directly on the mag-stripe card; a tape printer
206 to print receipts for customers and/or print batch history for the
clerk or agent responsible for administering the encoding machine's 200
operation; a communications modem 207 which can receive and initiate data
transmission over commercial telephone lines or other suitable media; and
an uninterruptible power supply 208.
The encoding machine 200 is accessed by the customer by pressing a
prominently marked key or button to indicate the beginning of a purchase
transaction. The message screen 202 asks the customer to identify the
location for which the purchase is to be made by either inserting a
previously purchased card 300 for that location, or by entering the
location account number on the 10-key numeric pad provided 203. If the
number entered is not a valid number, the customer will be so advised by a
message on the screen 202. If the number is valid, the location address
for that account will be shown on the message screen 202, and the customer
will be asked to verify that this is the location for which he wants to
purchase a card 300 by pressing the indicated button, or to otherwise
abort the process by pressing the cancel button. When the "proceed" button
is pressed, the message screen 202 will instruct the customer to insert
one or more paper currency bills into the currency recognizer slot 204,
and to press the indicated button when all the currency for this
transaction has been inserted. As each currency bill is inserted, its
denomination is read and stated on the message screen 202 for the customer
to verify. When the full amount of currency for the transaction has been
inserted, the customer instructs the CPU 201 to encode the data string to
be written to the mag-stripe card 300, and present it at the write head of
the encoder 205. When the data has been written to the card 300 and
verified, the printer 206 produces a printed receipt for the customer,
with a printed copy remaining in the encoded machine 200 for later audit
by the on-site administrator.
For bilingual communities, the unattended encoder 200 will present the
customer the option of having the instruction on the message screen 202
presented in an alternate language, such as Spanish or French.
The encoding machine 200 is accessed by the on-site administrator by means
of a conventional metal key. The key allows access to the interior of the
encoding machine 200 so that the cash may be removed, the receipt tape
removed and/or replaced, and the card supply replenished. This key also
allows access to a second "administrative menu" which the on-site
administrator uses to read various values regarding status and
transactions at the encoding machine 200. The on-site administrator is not
necessarily an employee of the utility company, but more likely a
contracted agent such as an apartment manager or the manager of a 24-hour
market. The on-site administrator operates the encoding machine 200 as a
cash drawer, removing the money periodically and depositing it in his/her
own business bank account. The utility receives its payment in the form of
a pre-authorized bank draft against the on-site administrator's bank
account. The draft is automatically printed by the host processor on a
daily (or other periodic) basis at the time the report of sales is
received from the encoding machine 200.
FIG. 3 is a block diagram of the customer premises equipment which consists
of three components: an indoor display device 400, a control device 500,
and a modified conventional meter 600. The functions of any two, or all
three of the devices may optionally be combined in a single housing where
an indoor location is not available or desirable, and/or it is more
economical to do so. The indoor display 400 and the control device 500
each have a microcontroller 401 and 501 and communications interface 402
and 502, and are programmed to pass status and control messages between
them. The microprocessors may be physically connected by wire, or
communicate through a commercially available powerline carrier system 452
which has been suitably adapted. The external features of the indoor
display 400 are a status window 403 to show selected numeric values, a
push-button 404 for changing the numeric values to be viewed, and a
swipe-type mag-stripe card reader 405 to receive information regarding
purchases which have been encoded on the mag-stripe card 300. Important
internal features include a clock 406 for measuring time, power failure
detection 407 to sense and react immediately to a loss of power, and
non-volatile memory 408 to maintain essential data through extended power
failures.
The major components of the control sleeve are a main power supply switch
503 to disconnect power when instructed by the programmed microcontrollers
401 and 501, a status signal light 504 to provide external indication of
low supply or power off condition, and power reset button 505 to provide
temporary power to the indoor display 400 so that mag-stripe cards may be
read if the main power switch 503 has been opened. This is required if the
powerline carrier communications 402 and 502 is being used in lieu of
direct wiring between microcontrollers 401 and 501. An optional external
communications port 505 is provided where it is desired to download stored
data to an interrogation device, or reprogram an internal calendar clock
chip. One or more optional load management switches 506 are provided to
control selected branch circuit loads when certain programmed conditions
exist; and one or more optional meter tampering detection switches 507 are
provided to sense and record selected meter tampering events. A low
voltage power supply transformer 508 provides power to operate both the
indoor display 400 and the control sleeve 500, except when the powerline
carrier communications options is used, the power supply transformer for
the indoor display 400 is located in the powerline carrier module 452.
Pulse conditioner circuitry 509 monitors the on-off state of two pairs of
photo cells 601 in the kWh meter 600 that are used to sense the rotation
of the meter disk 602. The number of meter disc rotations counted are used
to calculate energy consumption and the value to be removed from the
Amount Remaining shown in the status window 403; and the time interval of
each disc rotation is used to calculate the Present Use of energy shown in
the status window.
Password Security
The sequential password described in the aforementioned prior art is
effective for communicating directly between two devices, and is
restricted to the next sequential message. Under that scheme, the
authenticity of each message delivered to the remote metering site is
validated by the sequential password, which changes following each
transaction or transmission. The next valid sequential password is an
encrypted code known only by the transmitting device and the receiving
device. The sequential password is formed by the Accounting Computer 100
in the utility office building. The indoor display 400 contains an
identical algorithm for decoding the sequential password and sensing its
authenticity.
In the preferred embodiment, the same prior art is used for constructing
the sequential passwords, but additional elements are incorporated to
allow multiple communication paths between the Accounting Computer 100 in
the utility office and the remote indoor display 400 located at the
customer site. Theoretically, there is no limit to the number of paths
allowed, as provided by the number of card encoding stations the utility
company determines are necessary to geographically cover their service
territory. As a practical matter, the number of communications paths
allowed is limited by the amount of internal memory made available in the
customer display device 400. In the preferred embodiment, the available
memory provided in display 400 allows seven different card encoding
stations 101 and 200 to be active between the Accounting Computer 100 and
the customer display 400. This will allow the utility customer to purchase
electricity at seven different geographic locations. The construction of
the password also allows for the purchase of more than one properly
encoded card 300 per day from each of these seven encoding machines 200.
The number of purchases provided per encoding machine 200 per day is
limited by the data memory provided. In the preferred embodiment, two
cards per day per encoding machine 200 are allowed.
For card encoding machines 101 which are operated in person by a cashier or
clerk, the process for receiving payment and encrypting cards 300 is
substantially the same as described in the prior art. Therefore, this
discussion will be confined to a description of the operation of the
unattended encoding machines 200. Two-way communications between the
Accounting Computer 100 and the unattended encoding machines 200 is
provided by an exchange of data diskettes or by commercial telephone
lines, accessed for brief periods by commercially available modems 107 and
207 incorporated into the Accounting Computer 100 and the encoding
machines 200. As each new customer display device 400 is installed at the
customer site, the device is provided with its identifying numbers by a
specially encoded initialization encoding card 300, and the new account
information is transmitted to all of the encoding machines 200 within a
proximate geographical area determined by the utility company. The
elements of this New Account Record transmitted to the encoding machines
200 are shown in FIG. 4, including Account Number 109, Street Or Apartment
Address 701, Communications Protocols To Be Used 702, Applicable Electric
Rates 703, and Password Root 704. This information is stored in a Location
Record (shown in FIG. 7) in the encoding machine 200 and used at the time
a card 300 purchase is made.
When the customer purchases a card 300 from the encoding machine 200, the
message encoded on the card will consist of the elements in FIG. 5,
including Date Of Next Rate Change 705, Date Of Termination Of Cold
Weather Protection 706, Maximum Electrical Load Allowed Under Cold Weather
Protection 707, Communications Protocols 708, Account Number 709,
Applicable Rates 710 (whether present or future), Password Root 711,
Password Suffix 712, Amount Of Purchase 713, and Today's Date 714. The
first seven elements 705-711 of this message are retrieved from the
Location Record (shown in FIG. 7) in the encoding machine 200, this
information having been provided by the Accounting Computer 100 at the
time of the last database update. The last three items 712-714 are encoded
by the machine 200 at the time of each purchase and added to the data
string written to the purchase card 300. The Password Suffix 712 is the
encoding machine 200 identification number; the Amount Of Purchase 713 is
based upon the amount of currency received from the Customer; Today's Date
714 is the cumulative number of days counted since the system's
"birthday," set as Jan. 1, 1987. (Where a calendar clock chip is not
available in the display device, this "days since birthday" system is used
for all date purposes).
The currency is inserted in a slot where it is captured and read by a
commercially available currency recognizing device 204, which is an
integral part of encoding machine 200. The customer identifies the
location for which the purchase is being made by means of a numerical
keypad 203, which is an integral part of the machine 200, or by inserting
a card 300 previously used for the same location into the card reader 205.
When a location number is entered, or the previous card is read, the
encoding machine 200 displays electronically on the message screen 202 the
address associated with the location number entered by the customer. This
is to allow the customer to verify that the ensuing purchase will be for
the correct location before currency is inserted into the currency
recognizer 204. The message screen 202 displays the denomination of each
bill inserted, and the total cumulative amount inserted. When the full
amount of currency has been inserted, the customer presses the appropriate
button to notify the machine 200 to proceed to encode the card 300.
Typically, once each day the Accounting Computer 100 will automatically
dial up each encoding machine 200 and request a report of the card
purchase transactions which have occurred since the last interrogation. If
telephone communication is not available or practical, the information may
be communicated by a transfer of data diskettes on a time schedule set by
the utility company. Each transaction will be reported in a separate
Transaction Record message with the elements of FIG. 6, including Account
Number 715, Password Root Used 716, Password Suffix Used 717, Amount Of
Purchase 718, Date And Time Of The Transaction 719, and Batch Number 720.
If there has been more than one transaction at the machine 200 for a single
account location, the transactions will be reported in chronological
order. Following the reports from all encoding machines 200, the
Accounting Computer 100 will update the utility company's database and
communicate back to the machines 200 the elements necessary to make valid
the next transaction. When a purchase is made at an encoding machine 200,
the update message transmitted back from the Accounting Computer 100 will
be sent only to the machine 200 which performed the transaction, not to
the other encoding machines in the network. The reason for this is that
the only change in the data in the Location Record (shown in FIG. 7) of
the encoding machine 200 for that account location is the password root,
and each machine 200 will be operating on its own separate password series
for each account location, as described in more detail below. However, if
there is a change in location status which affects rates or protocols,
those messages will be sent to all the encoding machines 200 to update
that account information in the Location File (shown in FIG. 7) of each
encoding machine 200 in the network. When there is a general increase in
the rates charged by the utility company, the Accounting Computer 100 will
send the appropriate messages to all encoding machines 200 for all
customer accounts.
Each encoding machine 200 will maintain in its database a record for each
active account it might reasonably be expected to support, based upon
geographic location, as determined by the utility company Each Location
Record comprises the fields of FIG. 7, including Account (Location) Number
721, Street Number And Name Or Apartment Number 722, Communications
Protocols 723, Applicable Rates 724, Password 1 Root 725, and Password 2
Root 76. If it is desired to have more than two cards per day available
from a single machine, additional Password Roots (3, 4, etc.) may be
provided. Generally, a purchase transaction will result only in a change
in the Password Roots.
Each encoding machine 200 will also maintain in its data base a record for
each transaction. Transaction Records will be retained until reported to
the Accounting Computer 100 each day, and then may be erased or retained
for a specified number of additional days, at the option of the utility
company. The elements in the Transaction Record are shown in FIG. 8,
including Account Number 727, Password Root Used 728, Password Suffix 729,
Amount Of Purchase 730, Date And Time Of Transaction 731, and Batch Number
732.
The password consists, in the preferred embodiment, of eight numeric
characters, five of which are generated by the Accounting Computer 100,
and three of which are affixed by the encoding machine 200. The first five
characters are referred to as the root, and are changed for each
transaction by means of the algorithm described in the prior art. In the
preferred embodiment, upon initialization of an account, the Accounting
Computer 100 generates two sequential password roots PWR1 and PWR2 for use
in the first two card encoding transactions, and communicates this
information to the geographically-appropriate encoding machines 200. When
the Accounting Computer 100 subsequently receives the message from the
first-used encoding machine 200 that the first card 300 has been encoded
using the first password root PWR1, it will transmit back to the
first-used machine 200 the next two password roots PWR2 and PWR3 which are
to be used. If two card purchase transactions are reported for the same
day from the same machine, the next two passwords transmitted back to the
machine 200 would be PWR3 and PWR4. While the preferred embodiment makes
available only two password roots per day, it is obvious that any number
of additional password roots could be provided, limited only by the memory
capacity of encoding machine 200 and customer location device 400.
When a card 300 is encoded by an encoding machine 200, it will expand the
password by affixing to the root PWR1 the machine's identification number
Ml to provide the complete password PWR1M1. If a second card is bought
from the same machine 200 on the same day, the second complete password
would be PWR2M1. When a customer location display device 400 is
initialized, it will receive instructions from the Accounting Computer 100
to accept a password that includes only the root PWR1 but any suffix Mx.
When the first transaction card 300 is used with suffix M1, the customer
display 400 will assign a set of three internal registers for exclusive
use by that encoding machine 200, and then calculate and store (or
otherwise be programmed and compare) the next three passwords which will
come from that machine 200, namely PWR2M1, PWR3M1, and PWR4M1. These
password roots will be calculated using the same algorithm as the office
computer, the algorithm having been assigned when the display device 400
received its initialization instructions from the Accounting Computer 100.
The customer display 400 will then accept next any of three cards 300
which carries one of the three passwords it has internally stored. When a
card 300 is used with any one of these passwords, the customer display 400
will generate and store the next following sequential password PWR5M1.
Thus, the customer display 400 will perpetually have available three valid
passwords for the first-used encoding machine 200. This allows the
customer to purchase two cards 300 at one time and keep one as a reserve
card, to be used at any time in the future without regard to the sequence
in which the cards are used.
When the customer display 400 accepts the first card 300 from the
first-used encoding machine 200 and assigns the 3-register password set
for use by that machine, it retains the original root PWR1 so that in
addition to that password set, the customer display 400 will accept a
password PWR1Mx for any value of "x" except "1." This allows the customer
to purchase a card 300 from a different encoding machine 200 than the one
first use. When a purchase is made from a second encoding machine 200 not
previously used by that customer, the complete password encoded on the
card would be PWR1M2, which is the original root but with a different
suffix. The customer location display 400 will recognize this password as
being from a new and different encoding machine 200, and will thus open a
second set of three registers, calculate, and store (or otherwise be
programmed to calculate and compare) the next three passwords which would
come from this second-used encoding machine 200. These passwords would be
PWR2M2, PWR3M2, and PWR4M2. At this point, the customer display 400 would
then have seven valid passwords stored, three from each of the two
different encoding machines 200, and it would continue to accept PWR1Mx
for any value of "x" now except "1" or "2." This same routine would be
exercised whenever a card 300 was purchased from an encoding machine 200
not previously used. The number of different purchase points allowed in
the preferred embodiment is seven, although the number could be more or
less, depending upon the memory capacity allocated to this function in the
customer location display device 400. When the capacity of the display
device 400 has been reached and a purchase is attempted from still another
encoding device 200, the customer will be advised that a purchase from
that machine cannot be made unless the utility company makes a service
call to clear and reset the display device 400.
Initialization of Display Device upon Installation
In the prior art, the procedure for installing the display device 400 at a
new location involved loading certain identifying information, including
the password scheme, into the device by means of an especially encoded
mag-stripe card. The preferred embodiment utilizes the same technique, but
with some additional information. In the preferred embodiment, the
initialization card now carries the following data:
1. Password scheme initialization;
2. Display and sleeve communications address information;
3. Number of meters;
4. Readings of each meter at installation; and
5. Energy (Watt hours) per pulse of each installed meter.
Item 1 was included in the prior art. Items 2 through 5 are site-specific
information which is not likely to change with time. Some of this
site-specific information was originally included in the data encoded on
the purchase cards 300 in the prior art, but has been shifted to the
initialization card in the preferred embodiment in order to allow space in
the purchase card date string for other information necessary for the
enhanced functionality of the preferred embodiment.
Rate (Tariff) Changes
The Accounting Computer 100 contains operating software which includes a
Rates File 109, and menu-selected CRT screen displays 201 which allow the
utility company employee to store and code any number of rate structures
for any number of customer classifications. Each customer location
contained in the Location File 110 is assigned a rate designator code at
the time of installation, based on the customer classification. When a
purchase card 300 is encoded for any location, the rate information is
included in the data string so as to instruct the customer display 400 the
rate at which the energy used is to be subtracted from the Amount
Remaining. When the rate values or rate structures change, it is desirable
to automatically change the rates stored in the customer display 400 as
close as possible to the time the utility company rate change goes into
effect, regardless of the schedule on which the customer buys the cards
300. This is of particular concern where a customer may make a very large
purchase just prior to a significant increase, in order to extend
appreciably the period of time which he continues to use the service at
the previous lower rate. Therefore, the data string encoded on the
purchase card 300 contains fields for both the present and future rate,
and the date the change is to be made. Where the rate structure is so
complex that the data for both present and future rates cannot be encoded
on a single card, the present rate data will be carried on the card until
a "future" rate is entered into the Rates File 109, after which the future
rate and data of change will appear on subsequent cards. The data will
indicate whether the rate shown on the card is the "present" rate or a
"future" rate. If a purchase card 300 is the first issued for a new
location, it will always carry the present rate, and the future rate would
not appear until the second card is issued for the location. The future
rate information is placed in the Rates File 109 as soon as it is known.
Where a calendar clock chip is not available in the display device 400,
the date is specified by the cumulative number of days since an arbitrary
beginning point, such as Jan. 1, 1987.
Retention of Data During Power Failures
It is necessary to retain all data regarding status and values in the
display device 400 throughout all power interruptions, regardless of
duration. This is done without the use of external batteries which have to
eventually be replaced, and in the preferred embodiment is accomplished by
the use of EEPROM technology within the microprocessor. In order to
maintain the day "count" following an extended power outage, the date of
each purchase is encoded on each purchase card 300, and this date is
compared with the internal date shown by the display device 400. If the
date of the card is earlier than the internal date, the internal date is
changed to the date of the card. This is not as precise as a calendar
clock chip, and is not suitable for precisely-timed functions such as
"time-of-day rates," but is quite suitable for effecting rate changes, and
is more accurate than pro-rating procedures used with present utility
billing procedures.
Interactive Internal Diagnostics
The prior art cited earlier provides for certain malfunction messages to be
displayed in the status window 403 of the customer display device 400
regarding errors in reading encoded cards 300. The preferred embodiment
extends the interactive internal diagnostic capability to areas beyond
card-reading errors. There are two categories of additional information
provided. (1) Certain abnormal states are presented as error messages in
the status window 403, and are of such importance as to override and
exclude other normal display functions until they have been investigated
and corrected. (2) Other information is simply stored internally and can
be examined by calling up a separate series of status displays. The
diagnostic displays can be called up by either the customer or utility
serviceman by depressing and holding down for a short period (e.g., 5
seconds) the select button 404 on the face of the indoor display device
400. This action instructs the microprocessor 401 to cycle through and
display in the status window 403 each value of the diagnostic series as
the button 404 is repeatedly depressed. The operator can return to the
normal display values by again holding down the select button 404;
otherwise, the microprocessor 401 will automatically return to the normal
display set after a pre-set period of time, typically 4 minutes.
The abnormal events or conditions that require prompt attention will alert
the customer by displaying a numbered "error message" in the status window
403. In the prior art, errors that relate to improper reading of cards 300
are numbered 1 through 6. In this invention, additional numbers are
assigned to identify other specific events or conditions, such as a dead
photocell in the disk-rotation sensor 601, surge protection 510 breached,
or other component or memory failures; or the fact that the meter 600 or
control sleeve 500 have been subjected to one or more tampering efforts.
For example, "Err 11" may be used to announce the failure of a photocell,
and "Err 20" to indicate the meter was removed by an unauthorized person.
Component failure events are announced immediately. Tamper event messages
will not necessarily relate the error message to his tampering activity.
When any of these abnormal-event error messages appear in the status
window 403, all other displays are inhibited and will not respond to the
select button interrupts. This is to increase the likelihood that the
customer will call the utility company office and report a malfunction and
permit the utility company to investigate and correct the abnormal
condition. The specific abnormal-event messages available in the preferred
embodiment will vary, depending upon the options selected. For example, in
display devices 400 equipped with a calendar clock chip, one message would
be "probably loss of correct time." Since the meter tamper detection
switches are an optional item, where they are not available, such messages
as "meter removed," "magnetic field present", or "slowed or stopped disk"
will not appear.
In the preferred embodiment, the diagnostic series of messages may also
vary with hardware options included with the indoor display 400 and
control sleeve 500. The basic set of diagnostic values include:
1. Cumulative kWh. This number should match the kWh on the mechanical
register of the kWh meter 600. The software program in the Accounting
Computer 100 provides for adjusting this value to match any new reading in
the event the kWh meter 600 is replaced with one having a different
reading on its mechanical register.
2. Account Location Number. This is to confirm that the printed number
affixed to the display housing 400 is the same as the one installed in the
microprocessor 401 when it was initialized.
3. Transaction number. This shows how many purchase transactions have been
executed by the microprocessor 401.
4. Number of meters attached to this display unit. (In the preferred
embodiment, this would be up to 3. This is to allow sub-metered appliances
such as electric water heaters which are served different promotional
rates to be monitored through a single display unit).
5. Meter Number. This is to distinguish between meter signals when more
than one meter is attached to a single unit.
6. Energy per Pulse. This is the watt hours represented by each pulse
generated by the disk rotation.
Low Supply Warning
In the prior art cited above, provision has been made to alert the occupant
that the power supply is low by blinking the numbers in the status window
403 and providing a brief audible tone once each hour by means of the
speaker 409. In the preferred embodiment, provision is made to suppress
the audible signal for a period of time at the discretion of the customer.
This suppression is accomplished by automatically and routinely inhibiting
the audible tone warning for a pre-set period of time (e.g., 8 hours)
following any time the select button 404 is depressed.
"Word Messages"
In the prior art cited above, low supply was indicated only by the blinking
display and periodic audible chirp of the display device 400, and various
error conditions were indicated by the letter "E" followed by a number.
The preferred embodiment expands this interaction with the customer to
include certain English language "word" messages to be presented or
alternately flash in the display window to make the condition more clear
to the customers. For example, when the amount remaining is less than four
days' supply, the blinking display alternately shows the word "buy" and
the amount remaining. The preferred embodiment also includes French and
Spanish equivalents of the English word messages. The language presented
in the status window 403 is determined by bit settings in the data stream
on the mag-stripe card 300. In countries where other languages are in
common use, non-verbal signals are used to indicate the status or
condition. In the preferred embodiment these messages are limited to those
letters which can be created from 7-segment displays, but it is obvious
that other messages or icons could be presented if more sophisticated and
more costly displays were used.
Landlord Alert Signal
A status light 504 is installed in the housing of the control sleeve 500 to
provide a visual indication to a landlord of the status of the electric
supply to the property, especially when it is unoccupied. This is to allow
the landlord to monitor the status without having to go inside and read
the status window 403 of the indoor display 400. The status light 504 will
normally be off, but will blink repeatedly when the low-supply warning of
the indoor display 400 is active, and will be continuously illuminated if
the amount of supply remaining is zero or negative. The blinking operation
of this exterior status light will be inhibited during the same periods
that the indoor audible signal 409 is suppressed. Provision is also made
to inhibit the operation of the exterior status light through software
coding by the Accounting Computer 100, when the "exterior status light"
field of the Location File 110 is coded "NO." This instruction will be
carried on the "initialization card" 300, rather than the "purchase
transaction card" 300. Typically rental property locations will be coded
"YES" to allow the exterior status light 504 to operate, and
owner-occupied property will be coded "NO" to inhibit operation.
Load Limiting
In the prior art cited above, the microprocessor 401 is programmed to open
the power switch 503 to discontinue the utility service when the amount of
pre-purchased supply reaches zero. The preferred embodiment expands the
programmed instructions to allow the option of continuing utility service
to any (or all) customers at a reduced level (limited load) when the
display microprocessor 401 is so instructed. This limited load option is
implemented by placing numerical values in two fields in the data string
encoded on the mag-stripe transaction card 300, said values then being
loaded into the designated registers of display microprocessor 401.
Customers eligible for extended service for limited loads without full
payment would be identified and approved by utility personnel, and
appropriate values entered into designated fields of their Location File
110 through the Accounting Computer 100.
The value in the first field establishes the level of utility usage which
will be allowed to continue as expressed in (for example) watts or amps,
but calculated and encoded as the minimum number of seconds allowed per
disk revolution. For example, a restriction of 5 amps at 240 volts is the
equivalent of 1,200 watts; and with a meter with a Kh of 7.2 and a
multiplier of 1, if the time period of a disk revolution is less than 21.6
seconds, the 5 amp allowable load is being exceeded and the power switch
503 will be instructed to open. The switch will remain open for a pre-set
period of time (e.g., 4 minutes) to allow the customer time to turn off or
disconnect the offending appliance(s). The power switch 503 will
automatically re-close at the end of the pre-set period and restore
utility service. If the time period of the next disk revolution is still
shorter than the instructions allow, the switch 503 will open again for
the pre-set period. Sampling of the load level may be integrated over
multiple revolutions of the meter disk 602 if desired, such that the power
stays on for one minute or more before being disconnected again because
the load continues to exceed the established limit. This OFF-and-ON cycle
will continue until the connected load is brought below the allowable
limit. However, if the condition is not corrected after one hour, the
cycle times will be extended to 12 minutes ON and 48 minutes OFF, or some
similar ratio. This provision reduces the number of OFF/ON operations of
the appliances in case no one is home to turn off thermostatically
controlled appliances whose loads exceed the allowable limit.
The value in the second field of data encoded on the mag-stripe card 300
establishes the day beyond which the Lifeline function will no longer be
allowed to operate. The Lifeline option is provided to allow utility
companies to respond to regulatory commission rules regarding "no winter
cut-off," therefore it is anticipated that this function will be activated
only during certain portions of the year, and possibly only with certain
qualifying customers. This "date of termination of cold weather
protection" instruction allows the utility company to terminate the
"limited load" provision at the end of the protected season, and also may
be set for shorter periods throughout the winter season (e.g., 14 days, 30
days) in order to require the customer to respond to a need for some
amount of payment at intervals shorter than a full winter season. The
ability to specify the "load level" and "duration" for each customer at
the time of each purchase allows the utility maximum flexibility in
setting different standards for different customers, based upon the
customers' unique utility requirements and their ability to pay.
In the prior art cited above, the Amount Remaining value remains fixed at
zero when the pre-purchased supply is exhausted. However, with service
being allowed to continue under the limited load provision described
above, it is necessary to accumulate and display negative values for the
Amount Remaining shown in the status window 403. When such negative values
are present, they are subtracted from the value of the next purchase
transaction. In such cases, the status display 403 will show the Amount
Purchased as it is encoded on the mag-stripe card 300, but the change in
Amount Remaining will reflect only the difference between the amount
purchased and the negative accumulation, and indeed, the Amount Remaining
could still be negative if the amount of the purchase is not larger than
the accumulated negative value. Since the end of the "protected season" is
generally established by law or regulation, the Accounting Computer 100 is
programmed such that in all cases it will encode the mag-stripe cards to
terminate the Load Limiter privilege in the display microprocessor
registers 401 at the end of the protected season. This is accomplished by
setting a "default" termination date that is encoded on the purchase cards
300 unless an earlier date is specified at the time of the transaction.
For any customer carrying a negative balance in the Amount Remaining
status window 403 at the end of the protected season, the power switch 503
will open and remain open until the customer makes a purchase of
sufficient value to bring the Amount Remaining into a positive balance.
When the customer's Amount Remaining value has run to zero and he is
operating under limited load conditions, two additional values become
available in the status window 403. One shows the present electrical load
in watts so the customer can see his present use in relation to his
allowed limit. If the service is interrupted because the limit has been
exceeded, the load level at time of disconnect remains present in the
status window 403. The other status display available under limited load
conditions is the number of days remaining before the lifeline protection
ends and the service is totally cut off.
Negative Accumulation of Fixed Charges
For most customer locations, when a property is temporarily vacant and the
utility service is not connected, no collections are made for either
energy used or for customer-related monthly fixed charges. In the prior
art cited above, if a property is vacant but there is a positive balance
in the Amount Remaining shown in the status window 403, energy may
continue to be used and the monthly customer-related fixed charge
continues to be subtracted on a pro-rated daily basis. If the property
remains vacant until the Amount Remaining reaches zero, the power switch
503 opens, in which case there is no further use of energy, and no further
fixed-charge draw is accumulated against the Amount Remaining. However,
the preferred embodiment provides an option for the utility company to
continue the fixed-charge draw and to show a negative accumulation for
specified accounts. This is for use at those customer locations where
fixed charges presently continue to accrue and be collected, such as
seasonal cabins or other intermittently-used facilities. The Accounting
Computer 100 and Location File 110 provide a field to specify whether
negative accumulation of the fixed charge is to be exercised. This
information is communicated to the customer location on the initialization
card 300, not on a regular purchase transaction card 300. In this special
case, if the Amount Remaining reaches zero, the microprocessor 401 program
code instructs the power switch 503 to open, terminating service to the
location, but the monthly fixed charge will continue to accumulate on a
daily pro-rated basis and show a negative Amount Remaining in the status
display 403. When the customer wishes to restore utility service to such a
location, it is necessary to purchase a transaction card 300 of value
greater than the accumulated negative amount shown in the status window
403.
Statistical Reporting of Energy Use
Electric utility companies typically read customer meters every working day
of the month and produce reports of kilowatt hour sales based on these
meter readings. Generally, these sales reports attribute kWh usage to the
month in which the meter is read, without any effort to apportion the
usage to the calendar months in which it was actually used. Such
traditional reporting methods are accepted as being statistically
acceptable, primarily because of the expense and difficulty associated
with alternative methods. The only time that utilities normally attempt to
prorate consumption for a meter reading period is when it bridges the date
of a rate change, or at the end of the fiscal year when it is required to
estimate unbilled revenue for accounting purposes.
Prepayment for utility service creates some new and different challenges in
statistical reporting which are addressed in the preferred embodiment.
While the actual charging for utility services used s accomplished very
precisely with the display 400 and sleeve 500 mechanisms and instruction
sets, even with complex multiple-step rates, the reporting of electric
consumption is somewhat less precise since it must necessarily be based on
statistical averages. Even so, it is no less precise than present
procedures used with monthly meter readings and billings. Prepayment
reporting is accomplished in the preferred embodiment by instructions
programmed into the Accounting Computer 100 as described below.
The Transaction File 111 maintains a record of each transaction for each
customer account, with information in as many as 55 different fields for
each transaction, depending upon the complexity of the rate structure.
These fields include such factual values as account number, customer name,
date, amount tendered, days since last purchase, transaction number,
amounts allocated to various taxes, password used, encoding machine used,
and various rate values. There are also a number of calculated values
which are derived and stored. These related to the kilowatt hours bought
and the kilowatt hours used. The kWh bought value is a mathematical
calculation based on the days since the previous purchase and the amount
paid at present transaction. It is the less accurate value, and is
provided for use in satisfying certain accounting functions.
The kWh used value is a mathematical calculation based on the days since
the last purchase and the amount paid at the previous transaction. The
mathematical calculation is complex and includes the following steps:
1. If a rate change occurred between the previous transaction and the
present transaction, the amount tendered at the previous transaction is
prorated, based on the number of subsequent days the old rate was in
effect and the number of subsequent days the new rate was in effect. For
example:
______________________________________
if x = old rate a = days old rate in effect
y = new rate b = days new rate in effect
then ax/(ax + by) =
percentage of payment allocated
to old rate
by/(ax + by) = percentage of payment allocated
to new rate
______________________________________
2. For each allocated payment value, the applicable rate structures and
taxes are used to determine the number of kilowatt hours which would have
been used over the specified time period to produce a prorated bill
equivalent to the allocated payment value. For example:
______________________________________
if $3.00 = monthly fixed charge
0.10 = cost per kWh for first 300 kWh/month
0.075 = cost per kWh for over 300 kWh/month
24 = days since previous transaction
40.00 = amount of previous purchase
______________________________________
First subtract the prorated monthly fixed charge of $2.40 (24/30*3.00),
leaving a net energy payment of $37.60. Then, for the 24-day period, 240
kWh (24/30*300) would be charged at the rate of 10 cents, at a cost of
$24.00. The remaining amount of $13.60 ($40.00-$2.40-$24.00) would be
divided by the rate of 7.5 cents per kWh to show 181 kWh was used at that
rate. Thus the total kWh used for the 24-day period is 421 (240+181). The
average usage per day is 17.54 kWh (421/24), allocated as 10 kWh per day
under the first rate block, and 7.54 kWh per day under the second block.
3. Having determined the average usage per day for the period, the
Accounting Computer 100 determines the number of days in the 24-day period
which fell into which calendar month, and stores those values for use in
future reports. For example:
If the previous purchase occurred on Apr. 20, 10 days' usage would be
allocated to Apr., and 14 days' usage would be allocated to May as
follows:
______________________________________
April May
______________________________________
First Block 100 kWh 140 kWh
Second Block 75 kWh 106 kWh
Total 175 kWh 246 kWh
______________________________________
These totals are accumulated with totals from earlier and later
transactions to produce total kWh usage reports for each calendar month of
each year. All kWh values available in the reports also have a companion
revenue value associated with each kWh block, also available for each
report.
System Security
In addition to the password method provided to protect against counterfeit
and fraud by customers of the utility company, the Accounting Computer 100
and its files 109, 110 and 111 are protected from fraudulent intervention
by the employees of the utility company through the following methods:
There are three levels of user access to the system, each protected by
operator specific passwords. Clerical operators have access to the
customer transaction functions through the use of their own personal and
unique passcodes. Supervisory operators have password access to a second
level of functions, such as changing of rates. The system administrator
has password access to a third level of functions including modification
of user passwords, system configuration, and maintenance. In all cases,
the date, time, and operator code associated with each and every
transaction, regardless of its nature, is recorded in an audit record,
such that all sales transactions and all changes made in an of the data
bases can be traced to the date, time and operator who made the entry.
System Malfunctions, Diagnostics, and Reset
The housing for the Control Sleeve 500 is designed such that access can be
gained to the Communications Interface 502 without removing the meter or
disconnecting electric service to the location. This is accomplished by
enclosing the electronics in a separate housing on top of the sleeve. By
removing the meter sealing ring and pulling the top housing forward about
one-quarter inch, it can be removed, providing access to the
Communications Interface 502. A laptop PC 650 with a diagnostic program is
connected into the system at this point such that all stored information
can be read, and all functions of the system tested for proper operation.
This diagnostic unit can be used to reprogram "initialization data," reset
lost or scrambled data, clear and reset the password registers if they are
full, or clear and reset the value when a customer is moving and requests
a refund.
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